我能找到的唯一功能是:gimp-color-balance,它采用适用的参数:preserve-lum(osity),cyan-red,magenta-green和yellow-blue。
我不确定要为这些参数传递什么值以复制标题中的菜单选项。
为了完成@ banderlog013的答案,我认为Gimp Doc指定首先丢弃每个通道的最终像素,然后拉伸剩余的范围。我相信正确的代码是:
img = cv2.imread('test.jpg')
balanced_img = np.zeros_like(img) #Initialize final image
for i in range(3): #i stands for the channel index
hist, bins = np.histogram(img[..., i].ravel(), 256, (0, 256))
bmin = np.min(np.where(hist>(hist.sum()*0.0005)))
bmax = np.max(np.where(hist>(hist.sum()*0.0005)))
balanced_img[...,i] = np.clip(img[...,i], bmin, bmax)
balanced_img[...,i] = (balanced_img[...,i]-bmin) / (bmax - bmin) * 255
我用它取得了很好的效果,试一试!
根据GIMP doc的说法,我们需要在红色,绿色和蓝色直方图的每一端丢弃像素颜色,这些直方图仅占图像中0.05%的像素,并尽可能地拉伸剩余范围(Python代码):
img = cv2.imread('test.jpg')
x = []
# get histogram for each channel
for i in cv2.split(img):
hist, bins = np.histogram(i, 256, (0, 256))
# discard colors at each end of the histogram which are used by only 0.05%
tmp = np.where(hist > hist.sum() * 0.0005)[0]
i_min = tmp.min()
i_max = tmp.max()
# stretch hist
tmp = (i.astype(np.int32) - i_min) / (i_max - i_min) * 255
tmp = np.clip(tmp, 0, 255)
x.append(tmp.astype(np.uint8))
# combine image back and show it
s = np.dstack(x)
plt.imshow(s[::,::,::-1])
结果与GIMP的“颜色 - >自动 - >白平衡”之后的结果非常相似
UPD:我们需要np.clip()
,因为OpenCV
和numpy
不同地将int32转换为uint8:
# Numpy
np.array([-10, 260]).astype(np.uint8)
>>> array([246, 4], dtype=uint8)
# but we need just [0, 255]